The Water Reservoir

Hidden beneath the grass-covered roof in front of you is one of Lorient’s least-known secrets: the Navy’s former freshwater reservoir. For a major military and commercial port, fresh water was every bit as valuable as salt or spices. It was needed to supply ship crews, serve the Arsenal shipyards, and meet the needs of the barracks.

In 1874, the ministry approved plans for the vast underground reservoir before you. Should you have the chance to descend inside on a guided tour, you will discover a space that looks almost like a medieval crypt. With a capacity of 3,105 cubic meters (about 820,000 gallons), the reservoir is supported by sixteen cement-concrete pillars beneath a series of magnificent groin vaults.

For nearly seventy years, this underground structure stored fresh water and distributed it under pressure throughout the Enclos du Port. Regularly opened to visitors during the city’s cultural events, this vast chamber of stone and concrete reveals just how essential control of the freshwater supply was to Lorient’s maritime ambitions. After that brief plunge into history, it is time to dive into the next part of the tour.